Lighting and material appearance can create cosmetic variation, while deck or underlayment movement can telegraph through shingles. GAF separates these possibilities rather than treating every uneven appearance the same way.
GAF technical bulletin: Visual issues with shingled roofs.
What this means for your roof
Lighting and material appearance can create cosmetic variation, while deck or underlayment movement can telegraph through shingles. GAF separates these possibilities rather than treating every uneven appearance the same way.
A useful question for your contractor
Ask for the cause to be documented before deciding whether correction is needed.
Ask for the answer to be tied to the actual roof condition and the exact product being installed. Keep the agreed repair or installation detail with your estimate and project photos.
Bulletin revision: February 1, 2021. This is the date of the manufacturer source, not a claim that this website guide existed on that date.
Read GAF: Visual issues with shingled roofs
This homeowner summary explains the cited bulletin. The complete manufacturer document and current product instructions govern the installation details. A requirement for one manufacturer or product should not be transferred to another without checking.